Escherichia coli is a very widespread, often pathogenic, organism which is found in the human as well as domestic animals. The organisms vary in their virulence. While the E. coli infection is a widespread problem, it is especially serious in the raising of pigs. It is known that newborn piglets have very low levels of immunity against infection. This level of immunity is extremely low with respect to enterotoxogenic E. coli. Under practical pig raising conditions, a substantial number of newborn piglets are infected with enteric colibacillosis which gives rise to acute diarrhea. The effects of this diarrhea, especially the dehydration accompanying it, are of such a level of acuteness that a substantial fraction of the piglets thus infected die during the first six days of life.
Attempts have been made heretofore to isolate immunizing factors and administer same to the piglets. One such approach was taken by Rutter et al (Infection and Immunity 13, 667/676 (1976)) wherein an exocellular factor designated K88 was administered to pre-partum sows whose colostrum was then fed to newborn piglets exposed to virulent E. coli infection. In tests carried out on four vaccinated and four unvaccinated litters of between five and eight piglets per litter, the mortality rate of piglets nurtured by vaccinated dams was 12% while that of piglets nurtured by non-vaccinated dams was 68%.
It should be noted that previous studies directed to the nature of the K88 antigens clearly establish that the K88 antigen is not a pilic antigen. Stirm et al (Journal of Bacteriology, 93 740 (1967)).
While these results indicate an improvement over no protection at all, a more effective vaccination procedure and substrate was sought.